Content .. 977 978 979 980 ..

Lexus SC300 / Lexus SC400. Service manual - part 979

195

B 4

BUCKLE SW LH

1–2 : CLOSED WITH DRIVER’S LAP BELT IN USE

B 5

BUCKLE SW RH

1–2 : CLOSED WITH PASSENGER’S LAP BELT IN USE

T18, T19

TENSION REDUCER SOLENOID LH, RH

2–GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION

: PARTS LOCATION

CODE

SEE PAGE

CODE

SEE PAGE

CODE

SEE PAGE

B 4

D 3

T18

B 5

P12

T19

: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR

CODE

SEE PAGE

JUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)

FLOOR WIRE

COWL WIRE

: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS

CODE

SEE PAGE

JOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)

BX1

FLOOR NO. 3 WIRE AND COWL WIRE (RIGHT KICK PANEL)

Ba1

FLOOR WIRE AND FRONT SEAT LH WIRE (UNDER THE FRONT LH SEAT)

Ba2

FLOOR WIRE AND FRONT SEAT LH WIRE (UNDER THE FRONT LH SEAT)

Bb1

FLOOR NO. 3 WIRE AND FRONT SEAT RH WIRE (UNDER THE FRONT RH SEAT)

: GROUND POINTS

CODE

SEE PAGE

GROUND POINTS LOCATION

UNDER THE CENTER PILLAR LH

UNDER THE CENTER PILLAR RH

1 2

1 5 1 6

B 4 , B 5

D 3

P 1 2

T 1 8 , T 1 9

O R A N G E

B L A C K

SERVICE HINTS

FOREWORD

This wiring diagram manual has been prepared to provide
information on the electrical system of the 1992 LEXUS SC300.

Applicable models:

JZZ31

Series

For service specifications and repair procedures of the above
models other than those listed in this manual, refer to the
following manuals;

Manual Name

Pub. No.

1992 LEXUS SC300 Repair Manual

Volume 1
Volume 2

1992 LEXUS New Car Features

RM260U1
RM260U2

NCF080U

All information in this manual is based on the latest product
information at the time of publication. However, specifications
and procedures are subject to change without notice.

TOYOTA MOTOR CORPORATION

Servicing vehicles with an SRS AIRBAG (referred to as the airbag in the
remainder of this manual) installed.
When handling airbag components (removal, installation or inspection, etc.),
always follow the directions given in the repair manuals listed above to
prevent the occurrence of accidents and airbag malfunction.

NOTICE

METER, ANALOG

Current flow activates a magnetic
coil which causes a needle to
move, thereby providing a relative
display against a background
calibration.

LED (LIGHT EMITTING DIODE)

Upon current flow, these diodes
emit light without producing the
heat of a comparable light.

IGNITION COIL

Converts low–voltage DC current
into high–voltage ignition current
for firing the spark plugs.

1. SINGLE

FILAMENT

GROUND

The point at which wiring attaches
to the Body, thereby providing a
return path for an electrical circuit;
without a ground, current cannot
flow.

Current flow causes a headlight
filament to heat up and emit light.
A headlight may have either a
single (1) filament or a double (2)
filament.

BATTERY

Stores chemical energy and
converts it into electrical energy.
Provides DC current for the auto’s
various electrical circuits.

CAPACITOR (Condenser)

A small holding unit for temporary
storage of electrical voltage.

CIRCUIT BREAKER

Basically a reusable fuse, a circuit
breaker will heat and open if too
much current flows through it. Some
units automatically reset when cool,
others must be manually reset.

DIODE

A semiconductor which allows
current flow in only one direction.

DIODE, ZENER

A diode which allows current flow
in one direction but blocks reverse
flow only up to a specific voltage.
Above that potential, it passes the
excess voltage. This acts as a
simple voltage regulator.

FUSE

A thin metal strip which burns
through when too much current
flows through it, thereby stopping
current flow and protecting a
circuit from damage.

FUSIBLE LINK

A heavy–gauge wire placed in
high amperage circuits which
burns through on overloads,
thereby protecting the circuit.
The numbers indicate the cross–
section surface area of the wires.

HORN

An electric device which sounds a
loud audible signal.

LIGHT

Current flow through a filament
causes the filament to heat up
and emit light.

METER, DIGITAL

Current flow activates one or
many LED’s, LCD’s, or fluorescent
displays, which provide a relative
or digital display.

MOTOR

A power unit which converts
electrical energy into mechanical
energy, especially rotary motion.

CIGARETTE LIGHTER

An electric resistance heating
element.

DISTRIBUTOR, IIA

Channels high–voltage current
from the ignition coil to the
individual spark plugs.

2. DOUBLE

FILAMENT

HEADLIGHTS

FUEL

(for High Current Fuse or
Fusible Link)

(for Medium Current Fuse)

GLOSSARY OF TERMS AND SYMBOLS

1. NORMALLY

OPEN

Opens and
closes circuits,
thereby
stopping (1) or
allowing (2)
current flow.

RESISTOR

An electrical component with a
fixed resistance, placed in a circuit
to reduce voltage to a specific
value.

RESISTOR, TAPPED

A resistor which supplies two or
more different non–adjustable
resistance values.

SENSOR (Thermistor)

A resistor which varies its
resistance with temperature.

SHORT PIN

Used to provide an unbroken
connection within a junction block.

SOLENOID

An electromagnetic coil which
forms a magnetic field when
current flows, to move a plunger,
etc.

SWITCH, DOUBLE THROW

A switch which continuously
passes current through one set
of contacts or the other.

SWITCH,
IGNITION

A key operated switch with
several positions which allows
various circuits, particularly the
primary ignition circuit, to
become operational.

Wires are always
drawn as straight lines
on wiring diagrams.
Crossed wires (1)
without a black dot at
the junction are not
joined; crossed wires
(2) with a black dot or
octagonal (

) mark at

the junction are spliced
(joined) connections.

RELAY, DOUBLE THROW

A relay which passes current
through one set of contacts or the
other.

SENSOR, ANALOG SPEED

Uses magnetic impulses to open
and close a switch to create a
signal for activation of other
components.

TRANSISTOR

A solidstate device typically used
as an electronic relay; stops or
passes current depending on the
voltage applied at “base.”

SWITCH, WIPER PARK

Automatically returns wipers to
the stop position when the wiper
switch is turned off.

SWITCH, MANUAL

SPEAKER

An electromechanical device
which creates sound waves from
current flow.

2. NORMALLY

CLOSED

RESISTOR, VARIABLE OR
RHEOSTAT

A controllable resistor with a
variable rate of resistance.
Also called a potentiometer or
rheostat.

2. NORMALLY

OPEN

RELAY

1. NORMALLY

CLOSED

Basically, an electrically
operated switch which may
be normally closed (1) or
open (2).
Current flow through a
small coil creates a
magnetic field which either
opens or closes an
attached switch.

(2)

SPLICED

WIRES

(1) NOT

CONNECTED

Content .. 977 978 979 980 ..